Antiviral Drugs Study Notes

Antiviral Drugs Overview

  • Main Classes: DNA and RNA viruses; further divided into subclasses based on strandedness.

  • Infection Process: Viruses need to adsorb, enter, replicate, assemble, and release to infect cells.

Mechanism of Action

  • Target Steps: Antiviral drugs can block viral entry, exit, or act within the host cell.

Drug Classification by Mechanism

  • Entry Inhibitors: Ex: Maraviroc (blocks HIV entry).

  • Uncoating Inhibitors: Ex: Amantadine (targets influenza A).

  • Inhibitors of Translation: Ex: Fomivirsen (blocks CMV mRNA).

  • Inhibitors of Replication: Ex: Acyclovir (chain termination in DNA), Ribavirin (inhibits viral RNA replication).

  • Reverse Transcriptase Inhibitors (RTIs): Ex: Zidovudine (thymidine analogue).

  • Integrase Inhibitors: Ex: Raltegravir.

  • Protease Inhibitors: Ex: Saquinavir (inhibits protein cleavage).

  • Release Inhibitors: Ex: Zanamivir, Oseltamivir (neuraminidase inhibitors for influenza).

Key Examples of Antiviral Drugs

  • Acyclovir: Guanosine derivative; DNA synthesis inhibition.

  • Ribavirin: Guanosine analog; affects RNA synthesis.

  • Maraviroc: CCR5 antagonist; inhibits specific HIV strains.

  • Amantadine: Impedes influenza A virus uncoating.

  • Oseltamivir/Zanamivir: Blocked viral release in influenza A & B.

Resistance and Side Effects

  • Resistance can arise due to rapid mutation (especially in RTIs like Zidovudine).

  • Common side effects associated with treatments, especially protease inhibitors, include nausea, metabolic changes, and lipodystrophy.

Special Considerations

  • COVID-19 Treatment: Remdesivir shows potential but efficacy remains unclear; acts as an adenosine analog affecting RNA synthesis.